Gruppen was written for 109 players divided into three orchestral units, each with its own conductor, deployed in a horseshoe shape to the left, front and right of the audience. The spatial separation was designed to keep simultaneously played, musically separate passages distinct from one another, but in some passages a single musical process passes from one orchestra to another. This setup required three discrete speaker systems at front of house.
Sound system designer Paul van Baasbank, an L-acoustics CVE (Certified V-DOSC Engineer) for the past decade, deployed eight Kivas under two Kilos per side for the centre stage, with a centre cluster of six Kivas for instruments that needed to come from this perspective. The left and right stages each had systems of seven Kivas under two Kilos per side, and there were two delays of six Kivas under two Kilos to create a mono mix for people at the back.
Van Baasbank began his design using L-Acoustics' Soundvision 3D software, working closely with sound designer Paul Jeukendrup to realise a loudspeaker system that could provide optimum localisation for the three orchestras, while keeping sufficient coverage and a controllable sound pressure level throughout the hangar.
"The big challenge was that there needed to be a mix of the amplified sound with the acoustic sound to get more sense of directness," he says. "The acoustic panelling and natural energy of the orchestra created a lot of first reflections, but the amplified sound of the Kivas blended perfectly to produce this effect without the audience realising the concert was amplified.
"I chose Kiva as I thought it would be the right box for the situation due to its precise horizontal directivity, and this turned out to be right for the production. It was challenging for all sorts of reasons - not least of all because the aircraft hangar, when empty, had a reverberation time of more than eight seconds. This was reduced to three seconds by Italian acoustic specialists Suono Vivo and Berliner Philharmoniker acoustician Ralph Bauer-Dieffenbach who treated the auditorium with acoustic paneling and baffles."
The cabinets were provided and installed by German rental company Wilhelm and Wilhalm.
(Jim Evans)
